DESCRIPTION: Extremely low frequency (ELF) electromagnetic fields (e.g., from power lines) have been implicated in carcinogenesis by epidemiologic, animal, and in vitro studies. The long term goal is to understand the role of ELF field-induced changes in gene expression in enhanced transformation. Preliminary data show that ELF magnetic fields do not alter the expression of the c-myc proto-onocogene in HL-60 cells as previously reported by others.To clarify further the limits of gene expression changes induced by magnetic fields in HL-60 cells, differential display PCR will be used to determine whether any genes are field-responsive in those cells. In contrast to the apparent lack of a magnetic field effect in HL-60 cells, their data do support a role of ELF fields in co-promoting neoplastic transformation of JB-6 cells. To provide a biological framework in which to understand potential gene expression changes induced by ELF magnetic fields, the magnetic field exposure conditions that give the highest transformation frequency will be defined. These results will not only confirm the ability of magnetic fields to serve as a co-promoter of transformation, but also will contribute to a stronger understanding of the risks associated with different environmental signals. The transcription factor AP-1 (composed of homo- or heterodimers of peptides from the fos and jun families) plays an important role in transformation of JB-6 cells, and ELF field- induced changes in fos and jun expression have been reported in other systems. Therefore, AP-1 activity will be measured in functional assays and expression examined from fos/jun genes during the ELF magnetic field-enhances transformation process.The resulting data will indicate whether ELF field co-promotion occurs through the same pathway as do chemical tumor promoters. If another pathway is indicated, differential display PCR will be used to identify the genes with altered expression in magnetic fields.